Added HMAC MD5 vectors to LibTestApp

- added new module hmac_md5_test.c to LibTestApp
- updated Makefiles
- vectors 6 and 7 are commented out because there is no API in
  the library to allow for computing MD5 over larger messages
  than a block size

Change-Id: Ifab8485473b52ad7d9af5b34076b74ce23a3016c